This invention relates in general to systems for use in surveying and the construction industry. More particularly the invention relates to a system for projecting a laser beam in a plane having a selected horizontal, vertical or graded angle attitude.
Heretofore different instruments and procedures have been used in surveying and in the construction industry for measuring or checking elevations, grade, dimensions from off-set lines, and the like. It is well-known to use a level instrument to establish a line of sight on a leveling or grade rod. Such procedures involve a high labor content because they require two operators, one for controlling the level instrument and the other for handling the grade rod. Moreover, these procedures are subject to a number of inaccuracies and errors such as from design limitations in the instruments and from misreadings by the operators.
Laser beam systems have also been employed in surveying and construction industry systems of the type described. In one of these systems a laser beam projector is utilized in place of the level instrument. At the location whose elevation is to be measured or checked a target or laser beam detector is employed to intercept the laser beam. The laser beam projector employs a rotating head for sweeping the beam in a horizontal plane, with visually readable level vials and manually adjustable screws being provided for orienting the projector in a level attitude so that the beam plane is level. Such systems are available from Spectra-Physics, Inc. of Mountain View, California under the designation of Rotolite (TM) Laser Beam Projector. While such systems provide many improvements over the conventional level and rod systems, they also present certain disadvantages and limitations. For example, the degree of accuracy is establishing a horizontal beam plane is dependent on the operator's skill and judgement in reading the level vials as he operates the adjusting screws. Moreover, where the operator moves away from the device to tend the target or beam detector, the laser beam projector can move out of level adjustment, as from being jarred, without the operator's knowledge so that subsequent measurements would be erroneous. Such prior systems have also not provided the capability of precisely setting and maintaining the laser beam in a vertical plane or at a selected grade angle. Where it is desired to provide a rotating laser beam it has heretofore been infeasible to enclose all components within a completely water-tight enclosure to permit its use when exposed to the weather, e.g. in laying sewer pipe. Moreover at present where it is desired to point the laser beam along a selected axis the beam projecting head has been manually rotated. Heretofore it has not been feasible to incorporate the beam projector into a water-tight enclosure while maintaining the capability of beam pointing. In previous laser beam systems the components such as a laser tube, optics system and level vials have been attached onto the outer housing so that any shock forces imposed on the housing are carried through to the inner components with the result that the same are subjected to damage such that the system can lose its alignment. Thus there is a requirement for a new and improved laser beam projecting system for use in surveying and in the construction industry.